it seems what you are saying is that you had a late payment penalty which Turbotax does not compute nor does it computer interest on such late payment. A late payment penalty (owing a balance not paid by the due date of the return) is different than an underpayment of estimated tax penalty (not having enough withholding and timely estimated tax payments to cover the minimum required. Turbotax does compute this unless the taxpayer checks a box asking the program not to)
